T1D: Meta-analysis finds benefits from surgery

A systematic review and meta-analysis has reported that obese patients with type 1 diabetes (T1D) can achieve reductions in weight, as well as improvements in glycaemic status reflected in both total daily insulin requirement and HbA1c after bariatric surgery. Ultimately, further research including randomized controlled trials is necessary to confirm these findings. The paper, ‘A Systematic Review and Meta-Analysis of Outcomes for Type 1 Diabetes after Bariatric Surgery’, was published in the Journal of Obesity.

“This systematic review and meta-analysis demonstrates that obese patients with T1D are able to achieve marked reductions in BMI after bariatric surgery,” they write. “Moreover, bariatric surgery not only leads to a substantial decrease in total daily insulin requirement but also improves long-term glycaemic control as evidenced by a statistically significant reduction in HbA1c postoperatively.”

The researchers from the University of Alberta, the Royal Alexandra Hospital, Edmonton, and the University of Calgary, Calgary, Canada, stated that the effectiveness of bariatric surgery for T1D ‘”remains controversial”. As a result, they carried out a review and mata-analysis of electronic databases to evaluate glycaemic control outcomes in obese patients with T1D after bariatric surgery.

A total of 13 studies were (86 patients) were included and the subjects had a mean age of 41.16+6.67 years (n=64) with a preoperative weight and BMI of 123.5+3.84 and 42.5+6.25 (n=86), respectively. The mean duration of T1D was 22.4+3.81 years.

Most patients received a roux-en-Y gastric bypass (69%), followed by sleeve gastrectomy and biliopancreatic diversion with 15% and 14% respectively, with two cases of adjustable gastric banding (2%). There were no deaths reported in any of the studies.

Weight loss outcomes were evaluated based on changes to BMI postoperatively at 12 months and at study endpoint, with eight studies reporting BMI at 12 months postoperatively (n=40); BMI at study endpoint was reported for all studies. There was a marked reduction in BMI postoperatively at 12 months and at study endpoint to 29.55+1.76 (p<0.00001) and 30.63+2.09 (p<0.00001), respectively (Figure 1).

With regard to changes to total daily insulin requirement and HbA1c, postoperative daily insulin requirement at 12 months and study endpoint was reported in seven (n=33) and ten studies (n=59), respectively. Preoperative weighted mean total daily insulin requirement was 98+26IU/d, which decreased significantly to 26+15 IU/d (p<0.00001) and 42+11IU/d (p<0.00001) at 12 months and at study endpoint, respectively. Of note, weight-adjusted total daily insulin requirement at baseline and postoperatively at study endpoint was reported in all but one study (n=76), which also decreased appreciably from 0.78+0.2IU/d/kg to 0.48+0.11IU/d/kg, respectively (n=40).

In terms of HbA1c, this was reported in eight studies at 12 months postoperatively (n=40); HbA1c at study endpoint was reported for all studies. Weighted mean preoperative HbA1c was 8.46+0.78 % (n=86), which decreased to 7.95+0.55% (p=0.01) and 8.13+0.86% (p=0.03) at 12 months and at study endpoint, respectively,

“The present study highlights the fact that the metabolic benefits of bariatric surgery in obese patients with T1D are not well studied and remain poorly understood,” the authors conclude. “…Previous studies have reported conflicting findings regarding improvement of diabetes associated complications and cardiovascular disease…Ultimately, further research including randomized controlled trials is necessary to confirm these findings.”